Secondary-battery electrode.



No. 724,856. PATENTED' APR, 7, 1903.

J. HAHMANN. SECONDARY BATTERY ELECTRODE.

APPLICATION FILED JULY 19, 1902. no MODEL] q/vi Bunsen mz NORRIS PETERSco. wno'roumouwunmumm u. c.

UNITED STATES- PATENT OFFICE.

JOSEF HAHMANN, OF BERLIN, GERMANY.

SECONDARY-BATTERY ELECTRODE.

s'Pno'IricATIon forming part of Letters Patent No. 724,856, dated April7, 1903.

Application filed July 19, 1902. Serial No. 116,157. (No model.)

To all whom it may concern:

Be it known that I, J OSEF HAHMANN,.3. subject of the Emperor ofGermany, residing at Waldstrasse 18, city of Berlin, Prussia, Empire ofGermany, have invented certain new and useful Improvements inSecondary-Bate tery Electrodes, of which the following is aspecification.

For secondary batteries I have produced a thin, light, and durableholder for the active material, and inthe claim I will point out theprecise improvement.

In the accompanying drawings, Figure 1 shows in perspective thereticulated plate which forms the basin or base-frameofmy improvedelectrode. Fig. 2isa cross-section of the same. Fig. 3 shows thereticulated cover-plate for the basin. Fig. 4 is a crosssection of thesame. Fig. 5shows in enlarged detail the corner part of the reticu'latedbottom base-frame. Fig. 6 shows enlarged a por-' tion of the reticulatedbottom base-frame, its reticulated cover-frame, and the active materialin the closure formed by the basin and the cover. Fig. 7 shows thecorner of the base-fra me and the cast bottom strands without theframe-lip and in about the relative proportions of the mesh formed bythe strands.

An oblong square frame 1 is molded'or cast with a reticulated bottomsurface or back 2 on one side, leaving the other side of the frame openor uncovered. This reticulated bottom surface is comparatively thin andis strengthened and stiffened by intermediate bars 3, dividing the thinbottom into compartments. The reticulated thin bottom or back 2 coversthe area within the frame-border, and the crossed strands forming saidscreen -surface are molded or cast with the frame and with theintermediate cross-bars, so as to form a bottom screen facing to theframe. The border of the base-framev stands above this screen-bottom andforms a sort of basin within the frame. The cross-bars 3 are flush withthe border of the frame, as seen in Figs. 2' and 5, and divide the basinand its reticu-' lated bottom or back into squares to support thebottom. Into the basin-closure formed by this frame and the reticulatedbottom the active material is packed and retained therein by thereticulated cover-plate 4, the border inner wall.

of which matchesor registers with the border of the base-frame andisfastened to the latter, preferably by soldering. This cover plate tisas thin as the reticulated bottom jecting from the inner wall edges ofthe base-.

frame flush with the back surface of the plate, as in Figs. 2 and 6, sothat the lip 5 and the screen-strands are on a plane with the face ofthe plate, and the lip will thereby serve to hold the active material inpacking it around and against the inner walls of the base frame, as inFig. 6. The border of thecover-p1ate4 is wide enough to extend oroverhang the inner wall of the base-plate to form a lip 6all around thiswall corresponding with the lip 5 all around the base-frame, and therebyhold. the active material Within the base-frame all around its I preferto make the screen-forming strands square in cross-section, so that theywill form symmetrical interstices, give greater rigidity to the frameand locks for the active mass, which will be pressed in the bolt tominterstices. The active material in the form of paste is packed in thebase-frame upon its reticulated bottom or back and smoothed off and'thecover-plate is placed on the open side of the base-frame, and the twoborder-frames are then soldered together, leaving the interstices of thecover-plate partially unfilled for the better circulation of theelectrolyte fluid in the battery-cell. The reticulated bottom of strandscrossing each other 'con'nect'the edges of the cross-bars and theframe-border, and the cover-plate with its crossed strands closes thebase-frame over its cross-bars and its reticulated bottom and holds theactive material intact and gives an efficient action to the electrode.

The base-plate, with its reticulated bottom and cross-bars, and thereticulated thin coverplate are molded or cast of a'nalloy of lead andantimony and form the current-collector in a way well understood in theart. As the electrode is used in the ordinary way and connected in thebattery-cell by positive and negative wires with the battery-poles inthe usual way, an illustration of such use is deemed unnecessary.

I have shown and prefer to mold or cast the 5 base-plate with thecross-bars, because the thin reticulated cover-plate can be soldered tothem, and thereby prevent the possible bulging of the cover-plate, as inFig. 6. I prefer to make the screen-strands compara- Io tively fine andthe mesh about an eighth of an inch. With a cover-plate of fine strandsthe cross-bars are important to give the mesh the required stiifness andstrength, and for this purpose the cross-bars are wide and divide themesh into squares. Were it not for dividing the bottom mesh of finestrands by the cross-bars they would be without support and liable tobreak away from the borderframe, so that it is the molding of the finemesh of the base-frame into compartments and the cover into squares bythe cross-bars that allows the grid mesh to be formed of fine strands,which gives the advantage of increased cnrrent-collecting surface.Looking at Fig. 1 it will be noted that the division of the bottom ofthe basin into compartments renders it possible to make the back of theframe of a fine light mesh, because the crossbars form a frame-closurefor each compartment, giving its bottom the required strength withlightness.

I claim- An electrode for secondary batteries consisting of a base-framehaving a continuous lip on its inner wall flush with one of its faces, aback of strands connecting the continuous lip, and cross-bars flush withboth sides of the frame connecting the back strands and dividing theback into compartments, the mesh bottom of each compartment bound andbraced by the cross-bars, and a cover formed of a border, cross-bars anda mesh of fine strands between the bars and providing a. lip overhangingthe base-frame lip.

In testimony whereof I affix my signature in presence of two witnesses.

JOSEF HAHMANN.

Witnesses:

A. E. H. JOHNSON, II. L. FRANC.

